Differential expression of genes from the homeobox A cluster in deep endometriotic nodules and peritoneal lesions

OBJECTIVE: To compare expression of homeobox A (HOXA) genes involved in the differentiation of the female reproductive tract in deep endometriotic nodules and peritoneal lesions. DESIGN: Prospective experimental study. SETTING: Academic gynecology research unit. PATIENT(S): Thirty patients undergoing laparoscopy. INTERVENTION(S): During laparoscopy, deep endometriotic nodules (n = 30) and peritoneal lesions (n = 11) were recovered. Eutopic endometrium and vaginal tissue (n = 30) were collected for control purposes. MAIN OUTCOME MEASURE(S): Quantification of HOXA-9, HOXA-10, HOXA-11, and HOXA-13 in deep nodules, peritoneal lesions, and control samples by real-time reverse-transcription polymerase chain reaction, and localization of HOXA-10 and HOXA-13 proteins by immunohistochemistry. RESULT(S): The HOXA-13 transcripts were detected in 29 out of 30 nodules, and their expression was significantly higher than in vaginal tissue, but they were barely detectable in endometrium and peritoneal lesions. Expression of HOXA-10 and HOXA-11 transcripts in deep nodules was similar to eutopic endometrium, and HOXA-10 expression was significantly lower in peritoneal endometriotic lesions. The HOXA-10 immunostaining was mainly localized in the stroma of deep endometriotic nodules, HOXA-13 in glandular structures and stroma, and neither of these proteins were detected in fibromuscular areas. CONCLUSION(S): Marked expression of HOXA-10 and HOXA-13 in the endometrium-like tissue of nodules but low expression in peritoneal endometriotic lesions supports the theory of differential origin of these two types of endometriosis.